Don't quite know how mounting your thermostat would create a heat sink. Usually a heat sink is something we put in the incubator that hold heat. Small jars of Water, Pieces of tile or brick. Once those thing get hot they hold the heat better than air and keep the temperature more stable than if you don't have anything at all in there. Even the Water Wiggle acts as a heat sink. It will heat up and not drop the temperature as quickly as plain air.

Hmmm, I was looking on wikipedia and it says a heat sink is something used to regulate temp, like you said, only it's supposed to help trip the thermostat or whatever it is that regulates the temp. I'm thinking it works like this, I could be wrong though which wouldn't surprise me.

You mount the thermostat to the heat sink. The heat sink heats up with the air, until it hits the max temp. Since the thermostat is mounted to the heat sink, the thermostat gets tripped to kick the light off. When the light goes off the heat sink loses heat at the same rate as the air, causing the thermostat to trip the light back on. Without the heat sink it may take longer for the thermostat to register the temp drop/increase.

That came another thread on homemade bators. A members hubby helped her with her wiring (he's an electrician I think?)

Anyhow, what he said was that the thermostat goes by the temp of the metal it's against...not the air temp. So by screwing the thermostat to an electrical box, it took the temp of the metal and didn' have the wild swings that most of the others had.

I hope that makes sense. If not, go up to the search icon on the blue bar up top, type in thermostat and metal or something and you should be able to come up with it.

Not sure if it was one of my replies that you read or not..
I wasn't sure what to call it..But I did use an electrical box to help the water heater thermostat figure out the temp..A water heater thermostat doesnt measure air temp usually..I was reading in the forums how someone else had used an electrical box to mount it to..(the one whose hubby did the wiring)
And tried it myself..
Seems to have worked..

I had the same problem using the Water Heater Thermostat. It allowed wide swings in temperature before turning on or off the light bulb, in my case. I have never tried another method of mounting it to avoid that problem but it would be worth a try. I have continued to use the Lamp Dimmer. It does require ones attention but you don't have a feeling of false security. If kept in a stable place, it works great. I use the homemade one for a hatcher only and it is only for three days so it work well.

I'm thinking about talking to my MIL about re-rigging a regular wall thermostat....and figuring out how to adapt it to two wires instead of 5....Don't know if it's possible, but she's HVAC so if it can be done she'll know how....thanks for the help!